Tullock and co-workers,
(Tullock, C. W.; Tebbe, F. N.; Mulhaupt, R.; Ovenall, D, W.; Saltarquist, R. A.; Ittel, S. D. J. Polym. Sci. Part A (1989) 27 3063; Collette, J. W.; Tullock, C. W.; MacDonald, R. N.; Buck, W. H.; Su. A. C. L.; Harrell, J. R.; Mulhaupt, R.; Anderson, B. C. Macromolecules (1989) 22 2851),
have obtained polypropylenes exhibiting elastomeric properties using alumina-supported bis(arene) Ti, Zr, and Hf catalysts with materials of heterogeneous composition comprising chains soluble in ethyl ether, hexane, heptane and octane, as well as octane-insoluble ones. Each fraction contains polypropylene chains considered to be uniform in structure. The total polymer exhibits poor elastomeric properties. Hysterisis effects showing 110% permanent set after 300% elongation were obtained.
Ewen et al. and Kaminsky et al.
(Ewen, J. A. J. Am. Chem. Soc. 1984 106, 6355.; Ewen, J. A. "Ligand Effects on Metallocene Catalyzed Polymerizations", in Catalytic Polymerization of Olefins; Keii, T.; Soga, K., Eds.; Elsevier, New York, 1986, p. 271; (c) Ewen, J. A.; Haspeslagh, L.; Atwood, J. L.; Zhang, H. J. Am. Chem. Soc. 1987 109 6544; Kaminsky, W.; Kuiper, K.; Brintzinger, H. H.; Wild, F. R. W. P. Angew. Chem. Int. Ed. Engl. 1985-24 507), described symmetrical ansa-metallocene compounds which also produce heterogenous mixture of polypropylenes; examples are rac-ethylene bis(indenyl) zirconium dichloride and rac-ethylene bis(tetrahydroindenyl) zirconium dichloride. We have discovered new nonsymmetric ansa-metellocene systems, exemplified by rac-ethylidene (1-.eta..sup.5 -tetramethylcyclopentadienyl) (1-.eta..sup.5 -indenyl)-dichlorotitanium (1) which produces homogeneous homopolypropylene having the attributes of a thermoplastic elastomeric (TPE) material, which properties are derived from intrinsic molecular characteristics of the macromolecular chain, and, unlike the hecerogenotis polymers of Tullock et al, which have poor elastomeric properties resulting from the blend of amorphous and stereo regular polypropylenes.